Technical Field
The present invention relates to a material for manufacturing contact lenses. More particularly, the present invention relates to a hydrophilic material for manufacturing contact lenses having low modulus, excellent water content and high oxygen permeability.
Description of Related Art
In the early years, hard contact lenses were mainly made of glass. The soft contact lenses were therefore developed to improve discomfort of wearing of hard contact lenses. The soft contact lenses can be classified into two categories, hydrogel contact lenses and silicone hydrogel contact lenses.
The hydrogel contact lenses are made from hydrogel materials, such as poly-2-hydroxyethyl methacrylate (p-HEMA). Since the limited material characteristics of hydrogel contact lenses, the oxygen permeability (Dk) thereof is only about 15 to 35.
Comparing to the hydrogel contact lenses, the silicone hydrogel contact lenses have higher oxygen permeability because they are made from siloxane macromer and hydrophilic monomers. Although the siloxane macromer structure is able to provide high oxygen permeability, the higher modulus thereof are therefore occurred at the same time, so as to induce contact lens-induced conjunctival straining (C.L.I.C.S) of wearers easily. Moreover, if the wearers wear the contact lenses in a wrong way, the sickness of eyes may occur more easily. Therefore, a novel material for manufacturing contact lenses is highly demanded to solve the aforementioned problems.